"The Chessmen of Mars" by Edgar Rice Burroughs is a science fantasy novel published in 1922. When Tara, princess of Helium and daughter of John Carter, crashes her flier in a storm, she finds herself captured by the horrific Kaldanes—large heads with crab-like legs who ride headless human bodies. Prince Gahan of Gathol sets out to rescue her, but conceals his identity as a humble mercenary. Together they must survive the deadly city of Manator, where captives fight to the death as living pieces in a giant chess game.